<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Validate
 * @subpackage Sitemap
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: Changefreq.php 17470 2009-08-08 22:27:09Z thomas $
 */

/**
 * @see Zend_Validate_Abstract
 */
require_once 'Zend/Validate/Abstract.php';

/**
 * Validates whether a given value is valid as a sitemap <changefreq> value
 *
 * @link       http://www.sitemaps.org/protocol.php Sitemaps XML format
 *
 * @category   Zend
 * @package    Zend_Validate
 * @subpackage Sitemap
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Validate_Sitemap_Changefreq extends Zend_Validate_Abstract
{
	/**
	 * Validation key for not valid
	 *
	 */
	const NOT_VALID = 'invalidSitemapChangefreq';

	/**
	 * Validation failure message template definitions
	 *
	 * @var array
	 */
	protected $_messageTemplates = array(
	self::NOT_VALID => "'%value%' is not a valid sitemap changefreq",
	);

	/**
	 * Valid change frequencies
	 *
	 * @var array
	 */
	protected $_changeFreqs = array(
        'always',  'hourly', 'daily', 'weekly',
        'monthly', 'yearly', 'never'
        );

        /**
         * Validates if a string is valid as a sitemap changefreq
         *
         * @link http://www.sitemaps.org/protocol.php#changefreqdef <changefreq>
         *
         * @param  string  $value  value to validate
         * @return boolean
         */
        public function isValid($value)
        {
        	$this->_setValue($value);

        	if (!is_string($value)) {
        		return false;
        	}

        	if (!in_array($value, $this->_changeFreqs, true)) {
        		$this->_error(self::NOT_VALID);
        		return false;
        	}

        	return true;
        }
}
